Abstract :
In the present exploration, stock solutions of Furadan (carbofuran, 3% G) and Rogor
(dimethoate, 30%) pesticides were prepared and added to the BG-11 culture media to obtain the
desired concentration of 100, 250, 500 and 1000 ppm. 10 g proportion of air dried soil was taken in
sterilized BG-11 medium (with different concentration of various pesticides) and incubated at 28
0 ± 2 C under 16/ 8 hours light/ dark cycles with 2- 5 K Lux light intensity. The algal forms appearing in
the culture flask were identified by using standard monographs after 30 days of incubation. A sum of
19 Cyanophyceae species appeared in the composite soil of the control flask belonging to 14 genera
and 6 families. The occurrence of blue-green algae remained almost unaffected even in the presence
of Furadan and Rogor pesticides at 100 ppm dose in the test soil. The survival percentage of bluegreen
algae was reduced upto 50% at 500 ppm of Furadan while 10.52% survivability was noticed
with Rogor only at 500 ppm dose level. The organophosphate, Rogor, was comparatively more toxic
than carbamate, Furadan against tested blue-green algae. However, higher concentration of these
pesticides significantly affects the survival showing high algicidal potential. The result of the
present study revealed that indiscriminate use of these pesticides may cause adverse effects on the
nitrogen fixing blue-green algae in crop fields, which has a direct effect on total productivity. The
sensitivity of different Cyanophyceae to pesticide application was found more predominantly in
sheath less heterocystous and unicellular forms than the heterocystous ensheathed and nonheterocystous
ensheathed forms.
Keyword :
Blue-green algae, Furadan, Rogor, Pesticides, Survival.